Welding pipes together involves heating the edges and joining them together and cooling, resulting in the creation of one solid pipe. Another technique involves heating a filling compound, that when cooled, results in a permanent joining of two or more pipes.
The integrity of a weld depends on the welder employing quality materials and methods while making the weld. If a material that needs welding has a temperature below the freezing point, the material should be preheated to above the freezing point before welds are made. Dryer environmental conditions are optimal for welding pipes.
Welding is typically employed to avoid the use of fittings to connect pipes in a pipe run. If fittings are used, pipes need to be threaded which can be a tricky procedure involving extensive equipment and unnecessary labor. Using fittings sometimes increases flow restrictions, which are unlikely if welds are employed instead.